The effect of experience on the hunting success of newly emerged spiderlings

Initial interactions with prey may affect a predator's subsequent foraging success. With experience, second-instar Misumena vatia spiderlings (Thomisi dae) that had recently emerged from their egg sacs oriented faster to fruit flies (Drosophila melanogaster) than naive individuals. Orientation time o f these spiderlings decreased rapidly for the first two to three runs (ever y third day) in a simple laboratory setting, and then remained low and rela tively constant. Time to capture a fly also declined initially, but subsequ ently became extremely variable, increasing prior to moult. Increase in cap ture time and the failure to capture prey appeared associated with impendin g moult, rather than satiation. Spiderlings oriented to prey more rapidly a t the beginning of the third instar than at the start of the second instar, suggesting that experience still enhanced performance after a moult cycle. Overall capture times at the beginning of the third instar, decreased from those at the end of the second instar, but did not differ significantly fr om the beginning of the second instar, although spiderlings gaining the mos t biomass had the shortest mean capture times. In a second experiment, time to orient and time to capture prey did not differ in naive, second-instar siblings run 1 and 3 days after emergence from their egg sacs. However, 3-d ay individuals that had captured prey each day (confiscated before they cou ld feed) oriented faster than naive 3-day-old siblings, but did not differ in the time taken to capture prey. Experience, rather than age or energetic condition, best explains these changes in performance. (C) 2000 The Associ ation for the Study of Animal Behaviour.